The number of people born per year in the US has slightly decreased over the past decade. In 2010, 3,999,386 people were born in the US. For comparison, there were an estimated 3,791,712 births in 2018, according to the official report.
One reason why the number of births in 2021 in particular is of interest is the coronavirus crisis. Some commentators have suggested that couples who are forced to spend time at home during quarantine may be more likely to have children, which would increase the birth rate. This however remains to be seen.
Resolution criteria: This question will resolve when a US government agency, most likely the National Center for Health Statistics, releases a final estimate of the total number of live births for all US states and territories between January 1 and December 31, 2021. The report will likely not be published until late 2022, which is why this question is expected to resolve by 2023. (E.g. the 2018 report wasn't published until November 2019.)